This invention relates to the field of antiperspirant deodorant products. More specifically, it relates to antiperspirant deodorant products comprising an antiperspirant salt and a water soluble polymer that comprises Brnsted acid groups and acts as a co-gellant for the antiperspirant salt when mixed therewith in the presence of water.
Cosmetic antiperspirant and deodorant products are known. Typical antiperspirant products comprise topically acceptable compositions containing a metal salt, such as an astringent aluminium or aluminium/zirconium salt, in combination with a cosmetically suitable vehicle. Typical deodorant products comprise topically acceptable compositions containing one or more agents that mask or inhibit the formation of unpleasant body odours; antimicrobial agents are widely used for this purpose. Such cosmetic antiperspirant and deodorant products may be available in a variety of product forms, for example as sticks, creams, soft-solids, roll-on lotions, aerosols, pump sprays and squeeze sprays.
Whilst such compositions provide a degree of antiperspirancy and malodour reduction, there can be problems associated with their use and there is always a desire for improved performance. A problem encountered by some people, is that the application of high levels of astringent antiperspirant salts leads to skin irritation. Others find similar problems with certain antimicrobial agents. Other problems include formulation difficulties with the high levels of active ingredients sometimes required. It has long been desirable to achieve excellent protection from body malodour without the use of high concentrations of conventional antiperspirant or deodorant agents. This could lead to antiperspirant and deodorant products being cheaper, easier to formulate (by virtue of the reduced amount of antiperspirant active used), or generally having improved sensory properties. Other benefits of requiring lesser amounts of conventional antiperspirant or deodorant agents include the reduced concentration on the body of such xe2x80x98foreignxe2x80x99 agents and the reduced impact on the environment, in terms of chemical usage and processing.
The above problems have been addressed in a number of ways in the past, examples including the use of certain polymers as antiperspirant actives. WO 93/24105 (Tranner) describes the use of particular water-insoluble film-forming polymers, with conventional antiperspirant salts being non-essential, optional components in the compositions of the invention. The examples given that include antiperspirant salt also comprise co-polymers of octylacrylamide/acrylates or PVP/acrylates. No reference is made to interactions between the antiperspirant salts and the polymers. References to film-forming polymers are also made in JP 2290810 (Nakagawa et al) and WO 95/27473 (Causton and Baines). An alternative approach is described in EP 701812 (Abrutyn et al), where porous polymer beads are claimed to be capable of absorbing sweat components.
Polymers have also been used to enhance the performance of antiperspirant salts by increasing the residual amount of antiperspirant salt on the skin. Thus, EP 222580 (Klein and Sykes) describes the use of dimethyldiallyl ammonium chloride (DMDAAC) polymers for this purpose.
The use of DMDAAC/acrylic acid-type co-polymers to thicken personal care products is described in EP 266,111 (Boothe et al) and EP 478,327 (Melby and Boothe). The latter of these patents discusses the thickening of metal-containing aqueous compositions by said co-polymers.
Aqueous compositions comprising an acrylic acid containing polymer and an antiperspirant salt are described in WO 98/50005 and WO 98/48768 (Ron et al). In these patents, the proposed invention relates to the reverse thermal viscosifying benefit of the polymer.
U.S. Pat. Nos. 5,194,262 and 5,271,932 (Goldberg et al) describe antiperspirant compositions containing microcapsules comprising an antiperspirant salt encapsulated within a water-soluble shell possessing a bioadhesive. Polyacrylic acid is disclosed as a possible component of both the water-soluble shell and the bioadhesive.
We have discovered that the performance of conventional antiperspirant salts can be improved by the addition of polymers that are capable of interacting with the antiperspirant salts on contact with the skin.
Thus, according to a first aspect of the present invention, there is provided an antiperspirant product comprising an antiperspirant salt and a water soluble polymer, characterised in that:
(i) the polymer comprises Brnsted acid groups and acts as a co-gellant for the antiperspirant salt when mixed therewith in the presence of water; and
(ii) the polymer is physically separate from antiperspirant salt prior to application.
According to a second aspect of the present invention, there is provided a cosmetic method of achieving an antiperspirancy and/or deodorancy benefit, said method comprising the topical application to the human body of an antiperspirant product as defined in the first aspect of the invention.
According to a related aspect of the invention, there is provided a cosmetic method of achieving an antiperspirancy and/or deodorancy benefit, said method comprising bringing together on the surface of the human body an antiperspirant salt and a water soluble polymer comprising Brnsted acid groups which, in the presence of water, acts as a co-gellant for the antiperspirant salt.
According to a third aspect of the present invention, there is provided a method for the manufacture of an antiperspirant composition, comprising the mixing, in a fluid carrier material, of an antiperspirant salt and a water soluble polymer, wherein said polymer comprises Brnsted acid groups and acts as a co-gellant for the antiperspirant salt, when mixed therewith in the presence of water, and wherein the polymer is physically separate from antiperspirant salt in the composition.
The interaction between the antiperspirant (AP) salt and the polymer, on application to the human body, is an essential factor in this invention. The interaction between the components is chemical in nature and results in a thickened or gelled state of matter. It is desirable that the interaction between the components does not occur significantly before they are brought into contact with the human body. Such premature interaction can result in numerous problems including unwanted thickening of the product, poor dispensing, poor sensory properties, and poor antiperspirancy and/or deodorancy performance. Avoidance of premature interaction involves keeping the polymer physically separate from the AP salt. This may be achieved by co-application of the components from independent compositions; such co-application being done concurrently or consecutively, with either the AP salt or the polymer being applied first.
Alternatively, a composition comprising a non-interacting mixture of the AP salt and the polymer may be employed. Such compositions comprise the polymer physically separate from the AP salt. Non-interacting mixtures of this kind are ones where intimate contact between the AP salt and the polymer is not possible. Mixtures of this kind include co-dispersions of the AP salt and the polymer in a non-solvent carrier material. Examples of mixtures that do not meet this criterion include a true solution comprising both AP salt and the polymer and mixtures comprising AP salt encapsulated by the polymer.
In a particular aspect of the present invention, compositions comprising a non-interacting mixture of the AP salt and the polymer are essentially non-aqueous compositions. Essentially non-aqueous compositions comprise less than 10% by weight of water, preferably less than 5% by weight of water, and most preferably less than 1% by weight of water, excluding any water of hydration associated with the AP salt. In addition to being essentially non-aqueous, many compositions comprising both the AP salt and the polymer comprise less than 20% or even less than 10% by weight of polar organic solvents, for example C2 to C4 alcohols (monohydric or polyhydric), like ethanol.
Polymers
The polymers of the present invention are water soluble and comprise Brnsted acid groups. In addition, the polymers act as co-gellants for the AP salt when mixed therewith in the presence of water, for example water in human sweat, at a temperature of 37xc2x0 C. or less. The co-gelation results in a thickened state of matterxe2x80x94that is to say, the three component system (polymer, AP salt, water) has a higher viscosity than that of an aqueous solution of either the polymer or AP salt alone. Without wishing to be bound by theory, it is believed that the co-gelation involves chemical interaction between electronegative groups on the polymer and polyvalent hydrated metal cations deriving from the antiperspirant salt.
A simple test that may be used to determine whether or not a polymer is able to act as a co-gellant in given as Example 1. The test consists essentially of mixing aqueous solutions of the polymer and the AP salt and looking for an increase in viscosity.
The water solubility of the polymers used in the present invention, when measured at 37xc2x0 C., is preferably 10 g/l or greater, more preferably 50 g/l or greater, and most preferably 100 g/l or greater. It is required that the polymers form true solutions, rather than dispersions, in water; such true solutions typically having an absorbance of less than 0.2, preferably less than 0.1 (for a 1 cm pathlength at 600 nm) measured using a Pharmacia Biotech Ultrospec 200 Spectrophotometer or similar instrument. It is also desirable that the polymer is water soluble at pH 7; the attainment of said pH generally requiring a certain amount of neutralisation of the Brnsted acid groups present.
The Brnsted acid groups in the polymer may be present in their protonated form or may be present in their neutralised form as salt groups. Both partially-neutralised and fully-neutralised acidic polymers may be employed as co-gellants in the present invention. Suitable Brnsted acid groups include carboxylic acid groups, sulphonic acid groups, and phosphonic acid groups. Carboxylic acid groups are particularly preferred. Brnsted acid groups are preferably present at a concentration of greater than 0.1 mmole per gram of polymer, more preferably at a concentration of greater than 1.0 mmole per gram of polymer, and most preferably at a concentration of greater than 3.0 mmole per gram of polymer. These preferred levels relate to monobasic Brnsted acid groups and should be reduced pro rata for polybasic Brnsted acid groups. Latent Brnsted acid groups, such as anhydrides or other groups that generate Brnsted acid groups on addition to water, may also be present.
Preferred polymers are organic polymers, in particular, organic polymers possessing only limited positive chargexe2x80x94for example, organic polymers having less than 50 mole %, preferably less than 25 mole %, of positively-charged monomer units. Especially preferred organic polymers are nonionic and anionic polymers. Typical polymers possess carbon backbones, optionally interrupted by ester or amide links.
The acid value of a polymer is a widely used means of characterisation. Acid values generally express the acidity of a polymer in terms of the number of milligrams of potassium hydroxide base required to fully neutralise one gram of the polymer. Thus, the unit of measurement can be abbreviated to mg KOH/g.
Many of the polymers of the present invention have acid values greater than 160. Preferred polymers have acid values greater than 320 or even greater than 450. Particularly preferred polymers have acid values greater than 580. These acid values are based on the polymer in its fully protonated state; that is to say, the actual in-use extent of neutralisation of the polymer is ignored in respect of the xe2x80x98acid valuexe2x80x99. Acid values may be measured experimentally or may be estimated theoretically. When using the latter method, acid anhydride groups present in a polymer should be counted as two acid groups, such anhydrides generally being hydrolysed to di-acids by potassium hydroxide.
The preferred carboxylic acid groups may be introduced into the polymer by inclusion of monomers such as acrylic acid, methacrylic acid, maleic acid, itaconic acid, crotonic acid, maleic anhydride, or itaconyl anhydride in the polymer. When the only source of Brnsted acid groups are anhydride monomers, it is required that the anhydride groups are at least partially hydrolysed prior to use of the polymer. Polymers comprising a mixture of any of the above acid and/or anhydride monomers may also be advantageously employed. Particularly preferred polymers are those derived, at least in part, from maleic acid and/or maleic anhydride monomers.
It is sometimes desirable to include other monomers in the polymer. Suitable monomers include methyl vinyl ether, C1-C8 alkyl acrylates and methacrylates, vinyl acetate, ethylene, and propylene. The inclusion of such monomers may aid polymer synthesis, ease handling and/or formulation of the polymer, and may improve the performance of the polymer as a co-gellant.
The molecular weight of the polymer is preferably in the range of 500 to 5,000,000, in particular 10,000 to 3,000,000 and especially 100,000 to 2,500,000. Selection of an appropriate molecular weight for the polymer may lead to benefits in terms of ease of formulation, product aesthetics (particularly product feel), and product performance.
The polymer is preferably incorporated into a composition in an amount of from 0.5% to 20% by weight, more preferably from 1% to 15% by weight, and most preferably from 2% to 12% by weight of said composition, excluding any volatile propellant present.
In certain aspects of the present invention, the polymer is used in particulate form. When used in such form, the polymer particles generally have sizes between 0.1 and 200 xcexcm, preferably with a mean particle size of from 3 to 50 xcexcm. When the antiperspirant is also used in particulate form, it is further preferred that the polymer be of similar particle size to the AP (vide infra).
The mean particle sizes referred to in this specification are volume means, as typically determined by light scattering techniques.
Antiperspirant Salts
Antiperspirant salts for use herein are often selected from astringent salts including, in particular, aluminium and mixed aluminium/zirconium salts, including both inorganic salts, salts with organic anions, and complexes. Preferred astringent salts are aluminium and aluminium/zirconium halides and halohydrate salts, such as chlorohydrates.
Aluminium halohydrates are usually defined by the general formula Al2(OH)xQyxc2x7wH2O in which Q represents chlorine, bromine or iodine, x is variable from 2 to 5 and x+yxe2x88x926 while wH2O represents a variable amount of hydration. Especially effective aluminium halohydrate salts, known as activated aluminium chlorohydrates, are described in EP006,739 (Unilever PLC and NV). Some activated salts do not retain their enhanced activity in the presence of water but are useful in substantially anhydrous formulations, i.e. formulations that do not contain a distinct aqueous phase.
Zirconium salts are usually defined by the general formula ZrO(OH)2-xQxxc2x7wH2O in which Q represents chlorine, bromine or iodine; x is from about 1 to 2; w is from about 1 to 7; and x and w may both have non-integer values. Preferred are zirconyl oxyhalides, zirconiun hyroxyhalides, and combinations thereof. Nonlimiting examples of zirconium salts and processes for making them are described in Belgian Patent 825,146, Schmitz, issued Aug. 4, 1975 and U.S. Pat. No. 4,223,010 (Rubino).
The above aluminium and aluminium/zirconium salts may have coordinated and/or bound water in various quantities and/or may be present as polymeric species, mixtures or complexes.
Suitable aluminium-zirconium complexes often comprise a compound with a carboxylate group, for example an amino acid. Examples of suitable amino acids include tryptophan, xcex2-phenylalanine, valine, methionine, xcex2-alanine and, most preferably, glycine.
It is highly desirable to employ complexes of a combination of aluminium halohydrates and zirconium chlorohydrates together with amino acids such as glycine, which are disclosed in U.S. Pat. No. 3,792,068 (Procter and Gamble Co.). Certain of those Al/Zr complexes are commonly called ZAG in the literature. ZAG actives generally contain aluminium, zirconium and chloride with an Al/Zr ratio in a range from 2 to 10, especially 2 to 6, an Al/Cl ratio from 2.1 to 0.9 and a variable amount of glycine. Actives of this preferred type are available from Westwood, from Summit and from Reheis.
Other actives that may be utilised include astringent titanium salts, for example those described in GB 2,299,506.
Antiperspirant salts are preferably incorporated into a composition in an amount of from 0.5-60%, particularly from 5 to 30% or 40% and especially from 5 or 10% to 30 or 35% of the weight of the composition.
The proportion of solid AP salt in a composition normally includes the weight of any water of hydration and any complexing agent that may also be present in the solid active. However, when the active salt is in solution, its weight excludes any water present.
The weight ratio of the AP salt to the polymer is preferably 25:1 or less, 1:10 or greater, particularly between 25:1 and 1:10, and especially between 10:1 and 1:5.
Frequently the AP salt may be present in a composition taking the form of a suspension in which the AP salt in particulate form is suspended in a water-immiscible liquid carrier. In such compositions, the particle size of the AP salts often falls within the range of 0.1 to 200 xcexcm with a mean particle size often from 3 to 20 xcexcm. Both larger and smaller mean particle sizes can also be contemplated such as from 20 to 50 xcexcm or 0.1 to 31 xcexcm.
Optional Additional Components
A carrier material for the antiperspirant salt and/or the polymer is a highly desirable additional component of the products of the invention. Compositions preferably comprise carrier material at a level of from 30% to 98%, or more preferably from 60% to 97% of the weight of the composition, excluding any volatile propellant present.
The carrier material may be hydrophobic or hydrophilic, solid or liquid. Preferred carrier materials are hydrophobic. It is highly preferred that the solid or liquid carrier material is fluid at the temperatures typically used to make the product form in question. Hydrophobic liquid carrier materials particularly suitable for use are liquid silicones, that is to say, liquid polyorganosiloxanes. Such materials may be cyclic or linear, examples include Dow Corning silicone fluids 344, 345, 244, 245, 246, 556, and the 200 series; Union Carbide Corporation Silicones 7207 and 7158; and General Electric silicone SF1202. Alternatively, non-silicone hydrophobic liquids may be used. Such materials include mineral oils, hydrogenated polyisobutene, polydecene, paraffins, isoparaffins of at least 10 carbon atoms, and aliphatic or aromatic ester oils (e.g. isopropyl myristate, lauryl myristate, isopropyl palmitate, diisopropyl sebecate, diisopropyl adipate, or C8 to C18 alkyl benzoates).
Hydrophilic liquid carrier materials that may be used include water and polar organic solvents. When water is used as a carrier material for the polymer and/or the antiperspirant salt, it is strongly preferred that the polymer and the antiperspirant salt are applied from independent compositions. This ensures that premature interaction does not occur between the components (vide supra). Polar organic solvents that may be employed include C1-C4 monohydric alcohols, for example ethanol and isopropanol, and polyols, for example propylene glycol, dipropylene glycol, glycerol, polyethylene glycol, and C2-C8 1,2-alkanediols like 1,2-hexanediol.
An additional component that can sometimes augment deodorancy performance is an organic anti-microbial agent. Most of the classes of agents commonly used in the art can be incorporated into products of the invention. Levels of incorporation are preferably from 0.01% to 3%, more preferably from 0.03% to 0.5%. Preferred organic anti-microbial agents are those that are more efficacious than simple alcohols such as ethanol. The preferred organic anti-microbials are also bactericides, for example quaternary ammonium compounds, like cetyltrimethylammonium salts; chlorhexidine and salts thereof; and diglycerol monocaprate, diglycerol monolaurate, glycerol monolaurate, and similar materials, as described in xe2x80x9cDeodorant Ingredientsxe2x80x9d, S. A. Makin and M. R. Lowry, in xe2x80x9cAntiperspirants and Deodorantsxe2x80x9d, Ed. K. Laden (1999, Marcel Dekker, New York). More preferred anti-microbials are polyhexamethylene biguanide salts (also known as polyaminopropyl biguanide salts), an example being Cosmocil CQ available from Zeneca PLC, preferably used at up to 1% and more preferably at 0.03% to 0.3% by weight; 2xe2x80x2,4,4xe2x80x2-trichloro,2-hydroxy-diphenyl ether (triclosan), preferably used at up to 1% by weight of the composition and more preferably at 0.05-0.3%; and 3,7,11-trimethyldodeca-2,6,10-trienol (farnesol), preferably used at up to 1% by weight of the composition and more preferably at up to 0.5%.
Structurants and emulsifiers are further additional components that are highly desirable in certain product forms. Structurants, when employed, are preferably present at from 1% to 30% by weight of a composition, whilst emulsifiers are preferably present at from 0.1% to 10% by weight of a composition. In roll-on compositions, such materials help control the rate at which product is dispensed by the roll ball. In stick compositions, such materials can form gels or solids from solutions or suspensions. Suitable structurants for use in such compositions include cellulosic thickeners such as hydroxypropyl cellulose and hydroxyethyl cellulose, fibre-forming structurants such as 12-hydroxystearic acid, esters of 12-hydroxystearic acid, amides of 12-hydroxystearic acid, stearic acid, behenic acid and di- and tri-glycerides thereof, N-lauroyl-glutamic acid dibutyl amide, 2-dodecyl-N,Nxe2x80x2-dibutyl-succinamide, and dibenzylidene sorbitol. Partially or fully esterified disaccaharides, for example cellobiose octanoates, may also be used, as may structurants like dextrin palmitate. Sterols (e.g. xcex2-sitoserol) and sterol esters (e.g. oryzanol) are also suitable for use, when used in combination. Emulsion pump sprays, roll-ons, creams, and gel compositions can be formed using a range of oils, waxes, and emulsifiers. Suitable emulsifiers include steareth-2, steareth-20, steareth-21, ceteareth-20, glyceryl stearate, cetyl alcohol, cetearyl alcohol, PEG-20 stearate, and dimethicone copolyol. Suspension aerosols, roll-ons, sticks, and creams require structurants to slow sedimentation (in fluid compositions) and to give the desired product consistency to non-fluid compositions. Suitable structurants include sodium stearate, stearyl alcohol, cetyl alcohol, hydrogenated castor oil, beeswax, synthetic waxes, microcrystalline wax, paraffin waxes, candelilla wax, dibutyl lauroyl glutamide, alkyl silicone waxes, quaternium-18 bentonite, quaternium-18 hectorite, silica, and propylene carbonate. Some of the above materials also function as suspending agents in certain compositions.
Further emulsifiers desirable in certain compositions of the invention are perfume solubilisers and wash-off agents. Examples of the former include PEG-hydrogenated castor oil, available from BASF in the Cremaphor RH and CO ranges, preferably present at up to 1.5% by weight, more preferably 0.3 to 0.7% by weight. Examples of the latter include poly(oxyethylene) ethers.
Certain sensory modifiers are further desirable components in the compositions of the invention. Such materials are preferably used at a level of up to 20% by weight of the composition. Emollients, humectants, volatile oils, non-volatile oils, and particulate solids that impart lubricity are all suitable classes of sensory modifiers. Examples of such materials include cyclomethicone, dimethicone, dimethiconol, isopropyl myristate, isopropyl palmitate, talc, finely-divided silica (e.g. Aerosil 200), particulate polyethylene (e.g. Acumist B18), polysaccharides, corn starch, C12-C15 alcohol benzoate, PPG-3 myristyl ether, octyl dodecanol, C7-C14 isoparaffins, di-isopropyl adipate, isosorbide laurate, PPG-14 butyl ether, glycerol, hydrogenated polyisobutene, polydecene, titanium dioxide, phenyl trimethicone, dioctyl adipate, and hexamethyl disiloxane.
Fragrance is also a desirable additional component in the compositions of the invention. Suitable materials include conventional perfumes, such as perfume oils and also include so-called deo-perfumes, as described in EP 545,556 and other publications. Levels of incorporation are preferably up to 4% by weight, particularly from 0.1% to 2% by weight, and especially from 0.7% to 1.7% by weight.
It should be noted that certain components of compositions perform more than one function. Such components are particularly preferred additional ingredients, their use often saving both money and formulation space. Examples of such components include the many components that can act as both structurants and sensory modifiers, for example silica.
Further additional components that may also be included are colourants and preservatives at a conventional level, for example C1-C3 alkyl parabens.
Product Forms
The products of the invention may comprise compositions taking any form. When the product comprises more than one composition, it is preferred that the compositions take the same form. Example compositions include wax-based sticks, soap-based sticks, compressed powder sticks, roll-on suspensions or solutions, emulsions, gels, creams, squeeze sprays, pump sprays, and aerosols. Each product form contains its own selection of additional components, some essential and some optional. The types of components typical for each of the above product forms may be incorporated in the corresponding compositions of the invention.
Roll-on compositions of the invention preferably have a low level of non-volatile emollient present, for example isopropyl myristate or propylene glycol at 0.2-2% by weight. Antiperspirant sticks have cyclomethicone as a preferred carrier fluid. Also preferably present are one or more ethers or esters previously mentioned as sensory modifiers; these materials can serve to mask deposits. Wash-off agents are also desirable in such compositions.
Aerosol Compositions
Aerosol compositions of the invention are a particularly preferred product form. Preferably the propellant is the major component in such compositions, comprising from 30 to 99 parts by weight, more preferably from 50 to 95 parts by weight.
The propellant is normally selected from liquified hydrocarbons or halogenated hydrocarbon gases (particularly fluorinated hydrocarbons such as 1,1-difluoroethane and/or 1-trifluoro-2-fluoroethane) that have a boiling point of below 10xc2x0 C. and especially those with a boiling point below 0xc2x0 C. It is especially preferred to employ liquified hydrocarbon gases, and especially C3 to C6 hydrocarbons, including propane, isopropane, butane, isobutane, pentane and isopentane and mixtures of two or more thereof. Preferred propellants are isobutane, isobutane/isopropane, isobutane/propane and mixtures of isopropane, isobutane and butane.
Other propellants that can be contemplated include alkyl ethers, such as dimethyl ether or compressed non-reactive gasses such air, nitrogen or carbon dioxide.
The base composition, which is mixed with the propellant, may comprise any of the following components as preferred additional ingredients: a carrier material (fluid), a fragrance, an emollient (e.g. isopropyl myristate or propylene glycol) or an anticlogging agent (in order to prevent or minimise the occurrence of solid occlusions in the spray nozzle). Further components may be added to mask powdery deposits, for example non-volatile oils, long chain alcohols (e.g. octyl dodecanol), ethers (e.g. PPG-14 butyl ether), or dimethicone fluids.
An aerosol composition is usually filled into an aerosol canister that is capable of withstanding pressures generated by the formulation, employing conventional filling apparatus and conditions. The canister can conveniently be a commercially available metal canister fitted with a dip tube, valve and spray nozzle through which the formulation is dispensed.
Methods of Manufacture
The details of the relevant methods of manufacture depend upon the product form concerned. For a product that is a composition comprising a non-interacting mixture of the AP salt and the polymer, the basic method comprises the addition of the AP salt and the polymer to a fluid carrier material, keeping the AP salt and the polymer physically separate. In this context, a fluid carrier material is one capable of flow at the temperature used during the manufacture of the product. It is essential that the mixing is done in such a way as to prevent chemical interaction between the AP salt and the polymer. In a particularly preferred method, an essentially anhydrous carrier fluid is employed. It is further preferred that the AP salt and polymer added to the anhydrous carrier fluid are present in particulate form.